Emergency procedures

We all know that petrol is dangerous material and spend our time trying to minimise the risks by safe methods of construction and so on. No precaution however is foolproof and there comes a time when petrol escapes from the safe location and then we have a condition of emergency.

There are all sorts of emergencies to which a petroleum officer may be called. I recall cases ranging from 40,000 gallons of aviation fuel on the surface of a lake to a complaint of fumes which turned out to be due to a lady's rather generous use of her nail varnish! I cannot cover all types in one talk and propose to deal mainly with leakages and spillages at filling stations and similar installations which are the most common occurrences.

To give an idea of the risk that may occur, let us consider the following examples. A room of 10 feet by 8 feet by 7 feet high will be made fully explosive by the vapour from two pints of petrol. The same room will be made fully toxic by one tenth of this amount, that is by four fluid ounces. In the absence of air currents to cause dispersion portions of the room could be fully explosive or toxic by even smaller quantities. The power of an explosion of such a volume could theoretically throw a largish car some 10 miles.

Now the title of this talk sounds neat and tidy and suggests perhaps that a code can be laid down for the necessary actions. This however is far from the case and emergencies seem to show new facets every time, and the best one can do is to lay down general principles to be followed with great emphasis on the need to be ready for the unexpected and not to jump to conclusions however similar the case may seem to be with previous ones.

I think we can make a rough division between two types of incidents. Firstly where notification is made by the person keeping petrol of a leak or suspected leak and secondly the case where notification is received from other persons complaining of petrol or petrol odour in their premises. Now in the first case if there is not already other physical evidence of leakage it is just as well to spend a little time in checking that there has in fact been leakage. In some cases quite a quick check has disclosed that the supposed leak was in fact only a piece of bad arithmetic. I remember one case where the first message was that a tank had leaked 900 gallons overnight, but after a few questions on how often the tank had been dipped and so on, it became clear that the loss could in fact have occurred over a period of three years and in fact eventual tests showed that the installation was sound and that the the loss was due to normal running losses over the whole of this period. This was a private installation and I think this sort of mistake is more likely to happen in that type rather than on filling stations where record keeping, although often far from ideal, tends to be somewhat more detailed. As well as bad arithmetic there are other things which can give rise to mistakes in quantities in tanks. For example, clogged vents will give rise to high readings on the dipstick just after a tank waggon delivery and low readings after the tank has been in use. Water in a tank, if it becomes high enough to

H. T. E. JACKSON, Senior Petroleum Officer, Greater London Council

cover the bottom of the dip pipe will also give rise to faulty readings. High vent pipes are another cause of innaccurate readings due to the varying weight of the petrol vapour in the vent pipe.

Now these first enquiries should give some idea of the general picture involved, that is whether the loss has been a large sudden loss in recent time or whether it has been a comparatively small seepage over a period of days, weeks or even months. It is important to get this idea as to what has been going on as it must colour one's judgement on the priorities for the next moves. If it is clear that there has been a large loss recently then there is a possibility of it turning up in the near future in some dangerous area and therefore a high priority for checking and warning nearby premises. As an example there was one case where 500 gallons were lost into the soil due to a tank waggon delivering into a disconnected offset fill pipe. Now it was quite clear that there had been this large recent loss and the priority was to check nearby premises and warn of the danger. In actual fact it was found that a seepage had already started into the basement boiler house of a block of flats next door to the premises. The boilers were automatic and unattended, and had they not been put out at once there would almost certainly have been a major explosion within an hour or less. In fact half an hour after the boilers had been put out neat petrol was running through the wall of the boiler house at a rate of some five gallons an hour. I think this case emphasises the need for prompt action in cases of this nature.

The most likely places that a seepage will reach are basements, G.P.0. ducts-which are very prone--cellars, railway tunnels, sewers and similar underground spaces. There are however also less likely places in which petrol does sometimes turn up. It can climb up walls by capillary action where damp courses are broken and give rise to contamination in ground floors. All premises of these types near to the occurrence should be visited to check whether any contamination has started and to warn occupiers of the possibility of it starting later so that they may recognise it and give notification as soon as it starts. It is surprising that, if not warned, people will notice smells and do nothing about it for some hours or daysthey may think it a smell of gas or onions being peeled or all sorts of strange things and they will not send notification until perhaps the situation has got really dangeroususually in the middle of the night or a weekend. So although one does not wish to start a panic it is necessary to give advance warning. It is also necessary to give warning to Drainage and other similar authorities whose installations may become involved.

Now to come to the matter of remedial action. Well, the first thing obviously is to stop any further leakage or outflow. Sometimes it is not clear from which part of an installation the leakage has occurred and until this has been established from records or by tests it is not possible to stop any more loss unless the circumstances are sufficiently serious to put the

whole installation out of use and have all tank contents uplifted at once. In a recent case spirit was seeping into a railway tunnel and although the actual quantity involved was not large the risk was considerable. The nearby filling station which was the most likely source of the seepage had no records available to indicate whether or not it was the source and the owners were therefore required to have all spirit uplifted at once. Following this, tests were applied and one tank was found to be faulty (as a matter of interest this tank was only seven years old). In other cases where the leakage is not turning up in a dangerous position, or is not likely to do so, it may be possible to test the installation section by section wit?out sterilising the whole. There is a useful quick check which can be made on suction lines which whilst not necessarily ~ositive in all cases, can be often a h~lpful indication of a po~s1bly leaking line which can then be put out of action pendmg proper pressure testing. This test is done by holding the hose nozzle in a suitable container with the valve held ~ully open. The pump is then switched on and spirit should issue from the nozzle at once. If there is any delay in the commencement of flow it indicates that time has been taken to P~ime th~ suction line and this can only be due to either the h1:1e havmg been partly emptied by leakage or by leakage back mto the tank past the check valve. In practice the check valves seem to hold pretty satisfactorily and the odds are on th~ .delay being due to a leak. Now this test is obviously more ?ntical as the length of time that the pump has been out of use m~reases. If the pump has been used just before the test there will not have been time for enough petrol to have leaked out ~f the line for a noticeable delay to occur (unless of course the hne has a whopping great hole in it). This test will not work on Avery Hardol or Beck self-service pumps. Examination of petr.ol records will often give an indication as to what part of t?e mstallation is at fault. In this respect I would like to mentio1:1 t~at there is nothing magical about the figure of 1 % which 1 ~ ~ften quoted as the maximum working loss. With a Pump grvmg over measure to the figure allowed by Weights ~nd Measures Reg~lations on re-examination the loss wou.ld e greater than this. On the other as · sociated pump have been working hand if ' for some a tank time at and its a figure of say 0.3 % and then start to show a loss of say 0.6 % it would .obviously be suspect although still well below I %. Remedial action for premises which are being contaminated by seepage depends a lot on the type of premises and the degree of danger to them. If just a slight seepage is occurring, say to the basement of a building, giving rise to some slight degree of vapour contamination, then good ventilation of the area concerned and the removal of any possible igniting sources such as electrical equipment, gas appliances and so on, may be cond'f 1 ions are sufficient. Frequent not worsening and inspections to · also warning see of that any occ~pa~ts of the building of the steps they should take to avoid nsk would also be necessary. Remember that in addition to fire and 1 · · · · · k f exp os10n nsks there is also a very defirnte toxic ns t~on: much lower ~oncentrations. Any concentration s~fficient

Jive an explos1meter reading should be treated with care ~~.a reading of 10% or more of the lower explosive limit will 1 ~ icate fully toxic conditions. I have known cases of people w 0 have noticed smells of petrol in their premises but have nf ot reported it at once and they have clearly been suffering r?m minor toxic effects such as sickness and headaches without 1· · h rea 1smg t at these were resulting from the smells.

If r ·d . 1qu1 petrol · 1s · reachmg a basement or similar space action will have to be taken to remove it as far as possible. If the seepage is not large it may be possible to mop it up with sand or to leave sand where it will absorb the seepage as it occurs and then to remove it for drying off in some safe area. If the spirit is collecting in a sump or manhole or similar space it will usually be possible to ladle or syphon it off into suitable containers. One way of dealing with small skims of petrol floating on water in manholes, etc., is to emulsify it with some form of detergent. Household detergents such as Omo and industrial detergents like Slix or Teepol work quite satisfactorily. The emulsification makes it easier to remove the bulk of the spirit with the water and any that is left behind will vapourise less quickly. If the quantity of spirit involved is not large it may be reasonable to flush the emulsion down any available drain.

Sometimes when the flow of spirit into premises is large, or the premises are particularly vulnerable due to their usage, it may be necessary to try and recover the spirit before it can reach them. This can be done by digging pits or trenches outside basement walls or by digging them near the source of leakage. I mentioned previously a case where spirit was getting through the wall of a basement boiler house. Had this seepage been allowed to continue the boiler house would have been out of use for months and the occupation of the flats over would have been hazardous. A trial pit was therefore dug outside the boiler house wall and the bulk of the spirit laying in the soil was recovered from this pit. When these sort of works have to be carried out it is important to remember the precautions to safeguard the workmen doin? th~m. Breat~ing apparatus may be necessary if they are workmg m excavat10ns or forced ventilation of the excavation and, of course, all possible precautions against making spar~s while drilling or digging. In some cases it may also be desirable for wo~kmen to wear safety harness in case they are overcome m the excavation.

In deep manholes and similar spaces it may not b~ possible to ventilate sufficiently to reduce vapour concentrat10n belo:V explosive limits. A measure of safety on. a te'.11porary_ basis may be achieved by putting dry ice, that 1s solid C02'. m the space where it will form C02 gas which is heavy and w1~l te~d to stay in the manhole with the spirit vapour and 1t will inhibit or make ignition much less likely. It also has the advantage of being a very cold material and it will cool the spirit and make vaporisation less. It will not,. of course, ~ed~ce the toxic hazard and in an enclosed space will add to this nsk since it is an asphyxiating gas. The quantity of dry ice needed is one pound for every eight cubic feet of vapoW.: space and safety will not be achieved until dry ice has vaponsed.

Now we come to the second type of situation where a complaint originates from someone with petrol or smell of petrol in their basement, tunnel or what hav~ y~u .. If onl.Y odour is present the first job may well be to decide 1f m fact rt arises from petrol or is due to a gas leak or other c~use .. The nose is a pretty good guide but not ~y any meai:is mfalhble, particularly as old petrol can change its smell qmte. a lot a.nd can come to resemble diesel or have a smell wh1c~

w~1lst unlike fresh petrol is quite typical and I can only de~cnbe 1~ as "stale petrol". The MSA explosimeter can help to differentiate between petrol and town gas by u.se of the ca~bon fil.ter and there are other meters which will also aclueve tlus. Gas engineers usually have meters which wi.11 establis~ positively if a smell is town gas. If liquid seepage is present rt may well be easier to come to a conclusion since to smell can be added appearance, volatility and flammability of which quick checks can be made. On a longer term basis, laboratory analysis

of the liquid may be useful. A point to be watched is that petrol can quickly change its colour and odour if it comes in contact with bitumen or tar damp-courses, cable wrappings and suchlike. It will also darken considerably with aging in the soil. A rough guess as to its age can sometimes be made if it has been laying on the surface of water. Where there is a petrol/water interface certain fungi grow and these can be seen as streamers hanging from the interface. Their growth is something in the order of one eighth of an inch per year.

The first priority will obviously be to safeguard the premises concerned and the same remedial measures I have already outlined will be applicable.

The next step, and this can offer many snares and delusions, is to find the source of the trouble. It will clearly be logical to start with the most likely source which will be the nearest storage to the contaminated premises-and uphill of it if there is any local gradient. So, if there is a filling station next door to the complaint this would be the place to start investigations but do not be convinced straight away that it must be the source. There have been several cases where the source was found to be other than the likely one and I would like to give you a few examples.

There was one where a hotel located on a hill had vapour coi;itamination in its basement. At the top of the hill was a fillmg station-the logical suspect-and this was investigated thoroughly without disclosing anything except some history of minor spillages. The smell in the hotel continued and finally was found to be due to leakage from a faulty s1;1ction line in a filling station located at the bottom of the hill. soil of this hill was very fibrous leaf mould and acted as wick. The petrol was travelling something like 500 feet horizontally and 100 feet upwards to reach the hotel basement.

In another case spirit appeared in a G.P.O. manhole over a long period. Although the quantities involved were not large, due. to the enclosed nature of the manhole, explosive concentrations were common. Very close to the duct leading to the manhole-some three or four yards-was a filling station, clearly the prime suspect, and everything possible was done rule out any leakage from this station. The seepage into fi he manhole co?tinued however. Some four or five hundred . eet away and slightly downhill of the manhole were two other

Installations which did not show any undue losses in their When one of these installations was put out of use occ_upiers moving away, the conditions in the manb quickly improved and although this case has not yet proved it seems extremely likely that the further s a ation was the culprit.

Anoth h .1 er. · "d mc1 ent involved the basement of a house in a built-up neighbourhood where intermittent smells of vicr°-t occurred. There were no storages in the immediate dr ?1 Y but the nearest ams lock-smell ' . up garages ones were investigated as were local . ' and every such possible source. The ma s cfontmued however and finally investigation of very old PS o the d' t · · gin 11 fl is net disclosed that a small watercourse oriowed over site of the house. This water course also which over a site which is now a filling station and at petrol ere had been a known leakage of 300 gallons of Prem. some three Years before. The distance between the two the about three miles. It appeared clear that some of t s a gradually wa ercourse t · . that could b 0 give seeped down the t? the trouble. run of the old buried There was not much vapour 't lf 1 se . e done m this case except keep a watch on the conce t t' · n ra ion m the basement until it finally cleared

Complaints often arise from petrol getting into sewers either by spills getting into gullies which are not intercepted or by leakages into the ground seeping through faults in drain pipes or sewers. Now obviously any liquid petrol will flow down with the water in the sewer, but many sewers are warm and under such conditions there may well be a flow of air upwards against the fall of the drain, and petrol vapour may therefore travel upwards with the air. Such a case happened recently where smells of petrol in the drains ofa hospital were found to originate from petrol leaking into the sewer hundreds of yards away and well downhill of the hospital.

These examples will serve to show that tracing the source of a complaint is anything but straightforward, but once the source has been found the actions already discussed concerning stopping further leakage and so on will apply.

Now I have been talking on the practical aspect of leaks and emergencies and the works which are necessary. One question which may be in your minds is "What powers?" As far as work on licensed premises are concerned the matter is pretty straightforward. The Association's Code recommends a licence condition which requires the licencee to take such steps and do such works as are necessary. I do not think however that such a condition could be held to cover works that are necessary off the licensed premises, but it is often possible to persuade the licensee or his petrol company to do such works if they are convinced that the fault lays with their installation. If dangerous conditions exist in other people's premises it is clearly a moral duty to advise and persuade them to take the necessary steps or to allow the licencee's or petrol company's workmen to do it for them. There is, however, no power to make them do so nor is there any power of entry into their premises to see if dangerous conditions exist. Fortunately it is nearly always the case that all concerned are anxious for safety and prepared to take any advice offered. It is perhaps worth bearing in mind the possibility of civil litigation for expenses or damages occasioned by a leak and therefore to be somewhat guarded in comments to people other than licencees. One may well be convinced of the source of a leak but without positive proof it would be unwise to make any unqualified statement as to its source or responsibility for it.

Help from Fire Brigade or Police may sometimes be necessary. Conditions may be such that Fire Brigade standby against a possible ignition is desirable or if roads need to be closed or the public diverted away from danger the Police will do this. It will usually be found that these authorities will look to the Petroleum Officer to advise on the scope and nature of the precautions necessary. Also on this matter of help from others it is as well to always have readily available the phone numbers of other authorities, petrol companies and so on who may be needed in an emergency. They will usually also be prepared to supply emergency numbers for use out of normal working hours.

I would like to summarise the headings which can be remembered as a working guide and they are:

Has it gone?

Stop any more going.

Where has it gone or may go to (or where has it come from).

Warn any others possibly at risk.

Safeguard dangerous conditions by removal of liquid, ventilation and removal of ignition risks.

How or why did the leak or spillage occur. The priority for these steps must be decided in the light of the particular case.